Permanent well completion apparatus



p 1959 G. H. TAUSCH ETAL 2,906,345

PERMANENT WELL COMPLETION APPARATUS Filed March 14, 1958 INVENTORS. GILBERT H. TAUSCH,

JOHN W. KENNEDAY, BY Z M ATTORNEY.

United States Patent PERMANENT WELL COMPLETION APPARATUS Gilbert H. Tausch and John W. Kenneday, Houston,

Tex., assignors, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla, a corporation of Delaware Application March 14, 1958, Serial No. 721,483

1 Claim. (Cl. 166-489) This invention is directed to permanent well completion apparatus for working over and servicing the upper zone of a dually completed well.

In permanent well completion operations, tubing strings are set permanently during the life of the well and various producing, workover, and servicing operations are performed through these permanently set tubing strings. The workover and servicing operations generally performed on permanently completed Wells include squeeze-cementing operations wherein existing perforations below the lower end of the tubing are cemented off, perforating or reperforating by means of wire line guns at the same or different producing zones or intervals, sand-washing operations, acidizing operations, and other remedial work. A full discussion of permanent well completion operations is described in Permanent Type Completions and Wire Line Workovers, The Petroleum Engineer, September 1956.

An object of this invention is to provide improved apparatus adaptable for permanent well completion operations utilizing two tubing strings and two tubular extenstone for working over and servicing the upper zone of a dually completed well.

This and other objects of the invention will be apparent from a description of the invention taken in conjunction with the drawing wherein the sole figure is a cross-sectional view of a well bore showing the apparatus of the invention arranged therein.

Referring more particularly to the drawing wherein identical numerals designate identical parts, in the figure is shown a borehole penetrating a plurality of productive zones or intervals 11 and 12. A casing 13 is arranged in the borehole and cemented therein by means of cement 14. Two coextensive, parallelly extending, eccentric tubing strings 15 and 16 are arranged in casing 13. The upper ends of the tubing strings connect to a dual well head assembly, not shown, arranged on the surface of the earth. An upper dual bore packer 17 is arranged adjacent the lower open end of tubing strings 15 and 16 and seals off the space or annulus A between the tubing strings and casing 13. The upper dual bore packer 17 may be the type shown in the Composite Catalog of Oil Field and Pipeline Equipment, 21st ed., page 849. Landing nipples 18 and 19 are positioned in tubing strings 15 and 16, respectively. These landing nipples may be of any desirable type for supporting tubular extension members as, for example, the type landing nipple disclosed in the Composite Catalog, vol. I (1952-53), 19th ed., on page 4063.

A lower packer 20 provided with dual bores 21 and 22 is arranged in well casing 13 between upper and lower productive zones 11 and 12, respectively. The lower dual bore packer 20 may be the type shown and described in Baker Oil Tools, Inc., Probational Technical Manual, Unit No. 796 (XXX), dated December 2, 1955. A tubular extension 25 provided with a hanger assembly 23, upper and lower sealing means and 31, respectively,

ICE

2 perforations 32, a closed lower end and an open Upper end is arranged to extend through the lower end of tubing string lS and through bore 21 of packer 20. Hanger assembly 23, which may be conventional supporting apparatus such as expansible dogs, engages landing nipple 18 to support tubular extension 25 in tubing string 15. Sealing means 30 Scale off the annulus between tubular extension 25 and tubing string 15 and sealing means 31 seals off the annulus between tubular extension 25 and the wall of bore 21.. Perforations 32 are arranged above and adjacent to packer 20.

A tubular extension 26 provided with a hanger assembly 24, upper and lower sealing means 33 and 34, respectively, perforations 35, a closed lower end and an open upper end is arranged to extend through the lower end of tubing string 16 and through bore 22 of packer 20. Hanger assembly 24, which is similar to hanger assembly 23, engages landing nipple 19 to support tubular extension 26 in tubing string 16. Sealing means 33 seals OK the annulus between tubular extension 26 and tubing string 16 and sealing means 34 seals off the annulus between tubular extension 26 and the wall of bore 22. Perforations 35 are located above productive zone 11.

In working over and servicing upper zone 11, the direction of fluid flow is preferably down tubing string 15 and tubular extension 25, through perforations 32', through perforations 35, and up tubular extension 26 and tubing string 16 to the surface of the earth.

For reverse circulation the direction of fluid flow is pref: erably down tubing string 16 and tubular extension 26, through perforations 35, through perforations 32, and up tubular extension 25 and tubing string 15 to the surface of the earth.

This arrangement of apparatus assures that material such as a cement slurry to be placed between packers 17 and 20 definitely covers the perforated interval 11. Also, large volumes of the material may be, employed without fear of depositing this material within upper packet 17; which deposition may foul packer releasing mechanism. That is, the location of perforations 3-5 assures the op erator that material placed between packers 17 and 20 cannot rise above perforations 35 except within tubular extension 26. Thus, at no time can plastic or cementitious material set within the upper packer and create an extensive fishing job. Further, this arrangement of apparatus assures that when reversing out the material deposited between packers 17 and 20, the flushing fluid enters the casing annulus above the deposited slurry and flushes the annulus clean to immediately above lower packer 20. Also, in the case of accidental flash setting of cement, the well production tubing strings 15 and 16 and the upper retrievable packer 17 may be readily recovered by breaking the tubular extensions 25 and 26, leaving only the remaining portions of the tubular extensions, cement and packer 20 to be drilled from the well.

If desired, a telescopic joint may be placed in one or both tubular extensions to facilitate proper spacing of the extension in lower packer 20. Or the tubular extensions may be spaced to properly seal in lower packer 20.

Additional advantages of the apparatus are: the plugs in the lower packer bores 21 and 22 may be retrieved by pulling on wire lines attached to fishing tools which engage tubular extensions 25 and 26, respectively. This avoids the problems involved in running wire line tools into the casing 13 between upper and lower packers 17 and 20, respectively, to retrieve separate individual lower packer bore plugs, such as loss of tools, difliculty in fishing operations, etc. Further, the apparatus of this invention assures that no debris may be accidentally circulated above such a separate plug positioned in a bore of the lower packer. In such cases, extensive washing operations may be required before the plug may be uncovered and removed.

It is important to note, also, that if an open-ended tubular extension and a plug are employed, two tools must be removed in, separate running operations instead of one tool in one running operation as with the combined tubular extension and plug shown herein. If time is a critical factor, such as when cement is setting, it may be difiicult or impossible to remove two tools before the cement sets. Tubular extension 25 may be provided with a reverse plug cutter or pressure-opened perforated nipple. Also tubular extension 25 may be provided with an equalizing plug in place of the plug shown. A combined pressureopened perforated nipple and equalizing plug suitable for use is shown and described in U.S. patent application Serial No. 589,333 by G. H Tausch, entitled Permanent Well Completion Apparatus, filed June 4, 1956, now U.S. Patent No. 2,822,048. Also, tubular extension 26 may be provided with a pressure-opened perforated nipple 'such as disclosed in the above noted application in place of perforations 35. It is not necessary to provide both tu bular extensions with an equalizing plug since equalizing pressures across one of the bores of packer 20 equalizes pressures across the other bore. In any event, if the pressure differential across lower packer 20 is not great, the equalizing plug apparatus may be omitted altogether.

Use of the pressure-opened perforated nipples facilitates testing of the various seals. The packing on the sealing means 31 and 34 are provided with openings in the center thereof, not shown, to transmit pressure from the interior of the respective tubing strings through the packing in order to test the packing. Thus, for example, assuming that the pressure operated perforated nipples are closed, then pressure applied within tubing string 15 tests packing 30 and 31 on tubular extension 25 up to the limit of the pressure required for opening the perforated nipple. If pressure is not sustained in tubing string 15, then packing 30 or 31 may have a leak. Packings on sealing means 33 and 34 on extension 26 are tested in a similar manner, except pressure is applied within tubing string 16.

Upper dual bore packer 17 may be tested by applying pressure in one or both of the tubing strings and observing flow in casing annulus A after one or both of the pres sure operated perforated nipples have been opened.

Having fully described the apparatus, objects, method of operation, and elements of our invention, we claim:

Apparatus for working over, and servicing a cased borehole penetrating a plurality of spaced-apart hydrocarbon productive intervals comprising two parallel, eccentric, co-extensive, spaced-apart first and second tubing strings arranged in said borehole, the lower open ends of said tubing strings being positioned above said uppermost productive interval, a first packer positioned on said tubing strings adapted to seal off the space between said tubing strings and said casing, a second packer provided with first and second spaced-apart bores therethrough positioned in said borehole between said uppermost productive interval and a lower productive interval adapted to seal off the space between said bores and said casing, a first tubular extension supported in said first tubing string and extending through said first bore, first and second sealing means adapted to seal off the annuli between the first tubular extension and the first tubing string and between the first tubular extension and the first bore, respectively, said first tubular extension being closed off at the lower end thereof and being provided with perforations above and adjacent said lower packer and a second tubular extension member supported in said second tubing string and extending through said second packer bore, said second tubular extension being closed off at the lower end thereof and being provided with perforations above said uppermost productive interval, and third and fourth sealing means adapted to seal oh. the annuli between the second tubular extension and the second tubing string and between the second tubular extension and the second bore, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,785,754 True Mar. 17, 1957 

